The present invention is in the technical field of glassware. More specifically, the present invention is in the technical field of drinking containers. More specifically, the present invention is in the field of insulating drinking containers.
It is known that when a cold drink or liquid such as beer is contained within a glass container, the contents of the glass will eventually warm to ambient room temperature. The rate of warming is proportional to the difference in temperature of the liquid and the surrounding environment and is also proportional to the effective thermal conductivity of the container itself. Furthermore, the heat transferred from the hand of the consumer accelerates the warming process and also induces an unpleasant cooling of the hand. Throughout the warming process, condensation occurs, creating water droplets on the outside of the container which are transferred to the hand and the supporting furniture, both of which are undesirable. The condensation also poses a safety hazard as the container may slip from the hand of the consumer as it is being picked up or held.
Containers designed to address the above concerns are known from the Prior Art. “Double-Walled” drinking vessels, e.g., tumblers, cups, mugs, etc., are widely available in the retail market. These vessels are typically constructed of acrylic, polycarbonate, or similar (typically transparent) plastic materials using an inner and outer container, each having sidewalls and a bottom. The two vessels are brought together and “nested” in such a manner as to allow for an insulating air gap between the inner and outer vessel at which time the two vessels are joined at their interface in a cemented, fastened, ultrasonic welded, or similar method.
While these containers address the above concerns of keeping a beverage colder for a longer period of time as well as preventing condensation on the outside of the container, many people do not like the “feel” of plastic and prefer the premium “feel” of glass for their cold beverages such as beer when freshly poured from a tap. Almost without exception, glass is used in finer restaurants and bars when serving cold drinks such as beer due to customer preference.
Double walled glass containers do exist; however, these containers are typically made from a borosilicate glass, which is a thermally shock resistant glass, and is used for hot beverages and have the fusion seam between the inner and outer walls at the rim of the glass where the consumer places their lips to take a drink. An example can be found under Bodum U.S. Pat. No. D553,437. The point of fusion, at the rim, creates a “bulbous” feel and is not desirable for cold drinks such as beer. Beer glasses typically made from a soda-lime based glass, have a single, thin-walled drinking rim which the consumer is accustomed to and finds more desirable. The rim shape is defined by the method of manufacture and is either a “cut-off” or “burn-off” which will be discussed further below.
As such, there is a need for a premium, double walled glass container that embodies a single, thin-walled drinking rim, incorporates a continuous outer surface, and exhibits an improved insulation effect through the use of an air-gap between the inner and outer vessel walls which results in both keeping a cold drink cold longer and eliminating condensation on the outer wall of the outer vessel. In addition, these containers must not only be aesthetically attractive and produced of a high quality standard worthy of being served in the fine restaurant and bar market, they must be produced in an economical manner to appeal to these markets.